Ries, A. (1996). Focus: The future of your company depends on it. New York: HarperBusiness.
Chicago Style CitationRies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
Cita MLARies, Al. Focus: The Future of Your Company Depends On It. New York: HarperBusiness, 1996.
Atenció: Aquestes cites poden no estar 100% correctes.